During laser-beam welding, significant evaporation of metallic components occurs at the laser beam flux used during welding. When these vapors condense and solidify forming very small particles, some of these particles can be expected to settle on the welded part. The plume which develops and the resulting plume deposits are undesirable with respect to performance considerations, particulate contamination, and for cosmetic reasons. The presence of particulate contamination in electronic assemblies is a very serious problem. In addition, the resulting plume created can interact with the laser beam so as to alter the coupling of the laser beam energy to the metal. If the plume can be eliminated or altered by a gas flow, then control of the thermal characteristics of the process can be improved.
It has been demonstrated that the laser plume and accompanying weld geometry can be altered by impinging a transverse flow of gas near the base of the laser plume. Use of the transverse flow of gas during laser welding has been observed to reduce weld porosity. Such approaches in an attempt to control the laser plume do not eliminate the plume but merely divert the plume to one side and thus change the plume geometry. While affecting the laser weld geometry, use of the transverse flow of gas generally results in an undesirable deposit of condensed particles at the downstream side of the weld.